The present invention relates to a progressive resistance system most commonly provided for a piece of exercise equipment. More particularly, the present invention relates to a means for generating in two stages, a resistance to an applied force. The first stage provides for a generally linear increase in resistance over the majority of the effective operational range of the invention. The second stage provides for resistance in a rapidly increasing fashion which comes to play in the later portions of the effective range of the invention.
By way of background, many systems have been devised for applying resistance to an applied force. The following United States patents describe systems exemplary of these prior art approaches:
______________________________________ 4,323,237 Adaptive Exercise Apparatus Jungerwirth 4,749,182 Variable Resistance Aerobic Duggan Exercise Machine 5,351,974 In-Line Skate Braking Cech Assembly 5,193,833 Bicycle Front Suspension, Reisinger Steering & Braking System ______________________________________
Because of the ever increasing interest in health and fitness, there have been a number of devices that have been built in order to facilitate exercise. These devices have taken on a variety of modes and configurations. One of the key design elements that must be addressed by these devices is how to present to the users, a range of resistance to the particular exercise being undertaken. Users present themselves with a range of strength and conditioning and thus require a range of resistances. Even with the same person, the level of resistance that the user desires will change over the course of a workout period. Initially, the user may want slight resistant as the user warms up and then may want to increase resistance during the main part of the workout and then finally may want to decrease resistance during an exercise-to-fatigue phase or may simply want a slight amount of resistance during a cool-down phase.
Various means have been used to impart varying resistance. One form is the use of standard center-pull caliper brakes which typically impart force along the two outside edges of a flywheel which is being rotated in some manner by the efforts of a user. These devices have only a single stage of resistance and are often hard to adjust in a reproducible manner.
There has been computerized exercise equipment in which resistance is generated by the application of a brake pad against a brake disk. The force applied to the brake pad against the brake disk is generated by a pressurized hydraulic cylinder or other like device under computer control so that the amount of resistance experience by the user is varied based upon measured parameters, such as heart rate, respiration rate, number of repetitions per time, etc.
These devices are complex requiring an electrical power source, either from a utility outlet or from a generator driven by the user. They also typically require a hydraulic pump and pressurized fluid lines. All of these components increase the cost, weight and complexity of the device.
Another type of resistance device seen in exercise equipment is used in association with inline skates. Inline skating provides a relatively inexpensive and fun form of exercise and has become quite popular. Along with general enhancements of the inline skates, braking devices have also been developed.
A braking pad is forced against the periphery of one of the inline skate wheels which has been fitted with a special friction surface. The pad is mounted on a pivoting lever. When one end of the lever is moved away from the wheel, the other end is forced closer to the wheel, urging the brake pad tighter against the special surface on the wheel, bring the skate and hopefully the user, to a safe stop.
The lever is actuated by a cable mechanism in which one end of the cable is attached to the one end of the lever and the cable housing is fixed in placed by attachment to the frame of the skate. The other end of the cable is terminated in an actuating device which is held in the hand of the user. When the user wishes to stop, he engages the actuator which causes the cable to be pulled though the housing and pulling the one end of the lever up, the other end of the lever then forcing the pad against the wheel and stopping the user.
Though this is a braking device, its primary purpose is to bring the rotation of the wheel to smooth but definite stop. The user of an exercise machine not only needs to hold the resistance at a reproducible and steady level but also to be able to change it easily to another reproducible setting.
None of the current devices for imparting resistance provide a means creating resistance in two or more stages and in a manner that is convenient for the user.